Solar cell module

ABSTRACT

A thin film solar cell module which comprises a first electrode layer, a semiconductor layer and a second electrode layer, which are deposited on a substrate and at least part of which is worked to partition these layers into a plurality of cells which are electrically connected with each other and sealed with an encapsulant. At least part of at least one of the first electrode layer, the semiconductor layer and the second electrode layer, which is located at the periphery of the substrate, is removed by mechanical means or by means of laser beam. The periphery of the connected solar cells may be surrounded by a high adhesive strength region.

This is a divisional of application Ser. No. 09/392,083 filed Sep. 8,1999, now U.S. Pat. No. 6,300,556 which application is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

This invention relates to a solar cell module, and in particular to athin film solar cell module which is useful for a power generation fromsunlight.

There is known the following method as one of the methods formanufacturing a thin film solar cell module. Namely, a transparentelectrode layer, a photoelectric semiconductor layer and a metal layer,which have been deposited on a light-transmitting glass substrate, areat least partially worked by means of an optical beam thereby topartition these layers into a plurality of cells to isolate one cellfrom another cell, which are then electrically connected with eachother, and after terminals are attached to these cells, the reversesurface (the surface opposite to the light-transmitting glass substrate)is sealed with an encapsulant such as a resin for protecting thepower-generating portions thereof, the resultant body being finallyfixed to a mounting frame.

The dielectric strength is one of the characteristics demanded for asolar cell module manufactured in this manner. The dielectric strengthof solar cell module can be determined generally by measuring thewithstand voltage between a terminal of solar cell and the frame.

The thin film solar cell is generally constituted by a lamination ofthin films such as a transparent electrode layer, a photoelectricsemiconductor layer and a metal layer, and most of these layers aregenerally formed through a vapor phase reaction. Accordingly, it isgenerally difficult, in the process of forming such a laminate throughthis vapor phase reaction, to restrict film forming area to so-calledactive portion of the solar cell. Occasionally, any of these layers mayextend also to the other surface of the substrate. If such a substrateis attached as it is to the frame, it is more likely that the electricpotential of the frame may become identical with that of the activeportion of the solar cell. Because of this, the conventional thin filmsolar cells are generally poor in dielectric strength.

With a view to overcome this problem, there has been proposed a methodwherein the active region occupying the central portion of solar cell iselectrically isolated from the peripheral region of solar cell, whichhas much possibilities of being electrically contacted with the frame,by making use of a laser beam which is employed in the patterning of thelayers at the occasion of electrical connection of cells. However, thesolar cell module manufactured by making use of this method isaccompanied with a problem that even though the solar cell exhibits anexcellent dielectric strength immediately after the manufacture thereof,this property of dielectric strength is sharply deteriorated when thesolar cell module is left in an environment of high temperature and highhumidity. Accordingly, this method has been found poor not only inmanufacturing yield due to a low reliability but also in productivity,thus making this method useless in industrial viewpoint.

The thin film solar cell module of this kind is especially accompaniedwith a problem that when it is employed out of door, water may bepenetrated into the active portion (power generating region) of thesolar cell, thus denaturing or corroding this active portion, resultingin a deterioration of the power-generating property thereof. One of thecauses of this problem is the penetration of water through an interfacebetween the substrate and the encapsulant at the peripheral portion ofthe solar cell module. Therefore, it is highly desired to prevent thepenetration of water through a peripheral portion of the solar cellmodule and to improve the weather resistance of the solar cell module.

BRIEF SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide a solarcell module, which makes it possible, while assuring a highproductivity, to ensure the insulation between the power-generatingactive portion thereof and the peripheral region thereof, or theinsulation between the solar cell module and the frame thereof.

Another object of the present invention is to provide a solar cellmodule, which is excellent in dielectric strength, free fromdeterioration of property due to a corrosion after sealing thereof andcapable of maintaining a sufficient strength of glass substrate, andwhich can be manufactured in a stable manufacturing process and in highproductivity.

Still another object of the present invention is to provide a solar cellmodule, which is capable of preventing the penetration of water once itis sealed with an encapsulant thereby making it possible to prevent thepower-generating property thereof from being deteriorated due to acorrosion by water, and which can be manufactured with highproductivity.

According to this invention, there is provided a thin film solar cellmodule which comprises a first electrode layer, a semiconductor layerand a second electrode layer, which are deposited on a substrate and atleast part of which is worked to partition these layers into a pluralityof cells which are electrically connected with each other and sealedwith an encapsulant; wherein at least part of at least one of the firstelectrode layer, the semiconductor layer and the second electrode layer,which is located at the periphery of the substrate, is removed bymechanical means or by means of laser beam.

According to this invention, there is also provided a solar cell modulewhich comprises a laminate layer comprising a first electrode layer, asemiconductor layer and a second electrode layer, which are deposited ona substrate and patterned thereby to partition these layers into aplurality of solar cells which are electrically connected with eachother and sealed with an encapsulant; wherein a periphery of theelectrically connected solar cells is surrounded by a high adhesivestrength region, and adhesive strength between the high adhesivestrength region and the encapsulant is larger than the adhesive strengthbetween the encapsulant and the electrically connected solar cells.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention, and together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is a cross-sectional view of a thin film solar cell moduleaccording to Examples 1 and 2;

FIG. 2 is a cross-sectional view of a thin film solar cell moduleaccording to Comparative Example;

FIG. 3 is a plan view of the thin film solar cell module shown in FIGS.1 and 2;

FIG. 4 is a cross-sectional view of a thin film solar cell module usingglass substrate with chamfered edge; and

FIG. 5 is a cross-sectional view of a thin film solar cell moduleaccording to Example 3.

DETAILED DESCRIPTION OF THE INVENTION

The solar cell module according to this invention will be explained indetail below.

An example of the thin film solar cell module is constructed such that afirst electrode layer (a transparent electrode layer), a semiconductorlayer and a second electrode layer (a reverse electrode layer) aredeposited on a substrate, and at least part of these layers is worked bymeans of a laser beam thereby to partition these layers into a pluralityof cells which are then electrically connected with each other.

As for the substrate, a transparent substrate such as a glass substratecan be employed. As for the first electrode layer, a transparentconductive oxide such as SnO₂, ZnO, ITO, etc. can be employed. As forthe semiconductor layer, a layer mainly consisting of silicon, i.e. alaminate structure, such as a p-type a-Si:H layer, i-type a-Si:H layer,and an n-type micro-crystalline Si:H layer can be employed. It is alsopossible to employ a laminate structure of polycrystalline silicon layerwhich is capable of forming a pin junction may be also employed. As forthe second electrode layer (a reverse electrode layer), Ag, Al, Cr, Ti,or a laminate consisting of any one of these metals and a metal oxidecan be employed.

Each of these layers is deposited by means of a CVD method or asputtering method, and then partitioned into individual solar cells witha predetermined interval disposed therebetween by means of laserscribing. Then, the neighboring solar cells are electrically connectedin series (or in parallel), thus forming a thin film solar cell module.

The thin film solar cell module according to a first embodiment of thisinvention is featured in that at least part of at least one of the firstelectrode layer, the semiconductor layer and the second electrode layer,which is located at-the periphery of the substrate, is removed bymechanical means or by means of laser beam.

The removal of at least part of at least one of the first electrodelayer, the semiconductor layer and the second electrode layer bymechanical means in the thin film solar cell module of this inventioncan be performed by means of a surface abrasion method or a mechanicaletching method employing a blasting of fine particles. The fineparticles to be employed in the latter method may preferably be 100 μmor less in particle diameter.

It is also possible, other than the aforementioned mechanical etchingmethod, to perform the removal of at least part of at least one of thefirst electrode layer, the semiconductor layer and the second electrodelayer, which is located at the periphery of the substrate, by is meansof laser beam. When a laser beam is employed, the removal of thesemiconductor layer and the second electrode layer can be easilyperformed without removing the light-transmitting first electrode layer,thus exposing the first electrode layer. As for the laser beam, a beamwhich is enlarged in beam diameter can be employed. Preferable range ofbeam diameter to be employed in this case is 100 to 500 μm.

The width to be removed at the periphery of the light-transmittingsubstrate may be determined depending on the dielectric strength and onthe effective surface factor, specific dimensions thereof being 0.5 mmor more, preferably 0.5 mm to 10 mm, more preferably 1 mm to 5 mm.

It is important to note that it has been found by the present inventorsthat since the surface of the thin film solar cell module is not smooth,the first electrode layer (a transparent electrode layer) which isdesired to be removed can be completely removed only under a verylimited condition as a matter of fact.

Therefore, when the entire thickness of the first electrode layer isforcibly removed, the underlying light-transmitting substrate may bedamaged, thus greatly deteriorating the mechanical strength of thesubstrate.

It has been found by the present inventors that it is possible, byperforming the sealing using EVA (ethylene-vinyl acetate copolymer) anda back film while allowing the transparent electrode layer leftremained, to prominently improve the adhesive strength of the interfacebetween the EVA and the substrate (a transparent electrode layer), thusmaking it possible to substantially prevent water from penetratingthrough a peripheral portion of the substrate.

Accordingly, in the case of the thin film solar cell module according tothe first embodiment of this invention, it is no more required to removethe entire thickness of a portion of the first electrode layer, thesemiconductor layer and the second electrode layer, which is located atthe periphery of the substrate. Namely, it has been confirmed that, evenif the sealing is performed while allowing the transparent electrodelayer left exposed, it is possible to ensure a high adhesive strengththereof with the resin, thus making it possible to prevent water frompenetrating through a peripheral portion of the substrate.

If the entire layers of the first electrode layer, the semiconductorlayer and the second electrode layer is to be removed, the removal bymechanical means may be effected also against the surface of thelight-transmitting substrate. In this case, a total removal thickness ofthe substrate, the first electrode layer, the semiconductor layer andthe second electrode layer, which are removed by the mechanical means,should be controlled within the range of 5 μm to 100 μm, more preferablywithin the range of 10 μm to 25 μm.

It is preferable in the thin film solar cell module according to thefirst embodiment of this invention to employ a light-transmitting glasssubstrate whose peripheral edge is free from a right-angled portion oran acute-angled portion in order to prevent the substrate from beingcracked during the use thereof. By employing such a substrate, a modulewhich is stable in mechanical reliability can be obtained. The reasonwhy the module becomes stable in mechanical reliability is as follows:

The temperature of the solar cell module employing a glass substraterises during use. If a temperature distribution occurs in the glasssubstrate, the glass substrate may be cracked. The temperaturedistribution is marked particularly at an early time on a winter day. Ifa crack is present at an edge portion of the glass substrate, the glasssubstrate may easily break down. When parts of an electrode layer and asemiconductor layer are mechanically removed, the glass used as asubstrate may be cracked. In particular, if the edge portion of theglass substrate has a right-angled portion or an acute-angled portion,that glass substrate is easily cracked. For this reason, it ispreferable that the peripheral edge of the glass substrate be free fromthe right-angled portion or the acute-angled portion.

The peripheral edge of the light-transmitting glass substrate may beformed into a polygonal configuration, or into an arcuate configuration.The shaping of the peripheral edge in this manner can be realized bymechanically grinding the right angle portion (chamfering) if theoriginal shape is of a right-angled edge, thereby forming it into apolygonal configuration. Alternatively, the peripheral edge of the glasssubstrate may be thermally fused thereby removing the right-angled edgeportion.

It is also possible to perform the chamfering of the peripheral edgethereby to manufacture a glass substrate having the aforementionedconfiguration. Specifically, the chamfering can be performed byemploying a disk-like grinding machine having an annular groove formedalong the outer periphery thereof and shaped to conform with across-sectional configuration desired to obtain, and by contacting theedge of the glass substrate with the annular groove moving through therotation of the disk-like grinding machine. However, any otherchamfering methods can be employed.

In the thin film solar cell module according to the first embodiment ofthis invention, the peripheral portion of the active region consistingof a plurality of cells which are isolated from each other andelectrically connected with each other is removed by mechanical means orby means of laser beam. As a result, it is possible to ensure anexcellent insulation throughout the entire periphery of the module.Further, since the substrate or the first electrode layer is exposed allalong the entire periphery of the module, it is possible to ensure anexcellent adhesion thereof with a resin, thus making it possible tosubstantially prevent water from penetrating through a peripheralportion of the substrate. Therefore, it is possible according to thisfirst embodiment to obtain a module excellent in dielectric strengthwith a high yield.

In the solar cell module according to the first embodiment of thepresent invention, the first electrode layer may be made of a metalelectrode, and the second electrode layer may be made of a transparentelectrode.

The thin film solar cell module according to a second embodiment of thisinvention is featured in that a periphery of the solar cell region (theactive portion or the power-generating region) is surrounded by a highadhesive strength region which is larger in adhesive strength to theencapsulant, thereby allowing the substrate and the encapsulant to bestrongly adhered to each other at the peripheral region of thesubstrate, thus improving the water tightness of the peripheral portionof the solar cell module.

According to the solar cell module of the first embodiment of thisinvention, the improvement of dielectric strength and of adhesion iseffected exclusively by the removal of the peripheral portion of theactive region, whereas, the solar cell module of the second embodimentof this invention is directed to the formation of a region which islarger in adhesive strength against the encapsulant at the periphery ofthe active region, though there are many aspects which overlap with thefeatures of the solar cell module of the first embodiment.

As for the material of the encapsulant, ethylenevinyl acetate copolymer(EVA), polyisobutylene, polyvinylbutyral, silicone, etc. can beemployed. As for the protective film, a vinyl fluoride film, a laminateconsisting of a vinyl fluoride film and an aluminum foil can beemployed. It is also possible to employ, as the protective film, a metalplate, a glass woven fabric, a glass nonwaven fabric etc.

The adhesive strength between an underlying material and the encapsulantcan be evaluated by measuring the vertical peel strength (JIS K6854) forinstance. Specifically, the vertical peel strength of EVA which had beenadhered as an encapsulant to an underlying material was measured, using,as an underlying material, a glass substrate, a transparent conductiveoxide such as SnO₂ constituting the first electrode layer, asemiconductor, and a metal constituting the second electrode layer. As aresult, the vertical peel strength of EVA was 15 kgf/cm or more (or thehighest value in this measurement) when the glass substrate was employedas an underlying material, and 14 kgf/cm when the transparent conductiveoxide was employed as an underlying material, which is much higher than0.5 to 4 kgf/cm which were obtained when the semiconductor or metal wasemployed as an underlying material. The peel strength varies prominentlydepending on the kind of metal and on the surface condition. Forexample, in the case of a refractory metal such as Cr, Mo, W and Ti, thevariation of peel strength is relatively small. However, in the case ofordinary electrode materials such as Ag and Al, the peel strengththereof was generally less than 3 kgf/cm.

Therefore, when the periphery of the solar cell region is surrounded bya region which is larger in adhesive strength to the encapsulant thanthat between the encapsulant and the electrically connected solar cells,e.g. by a region whose vertical peel strength to the encapsulant is 3kgf/cm or more, more preferably 10 kgf/cm or more, it becomes possibleto improve the water tightness and weather resistance of the peripheralportion of the solar cell module.

According to this second embodiment of this invention, the region havingsuch a high adhesive strength can be realized by (1) the exposed portionof the first electrode layer consisting of a transparent conductiveoxide, (2) the exposed portion of the substrate, or (3) a layer of ametal selected from the group consisting of Cr, Mo, W and Ti.

If the region having such a high adhesive strength is to be constitutedby the exposed portion of the first electrode layer consisting of atransparent conductive oxide, a method may be employed wherein thesecond electrode layer and the semiconductor layer that have beendeposited or laminated at the peripheral portion of the substrate bymeans of a CVD method or a sputtering method for instance are removed bymechanical means or by means of laser beam. This removing method bymechanical means or by means of laser beam may be the same as explainedwith reference to the aforementioned first embodiment.

If the region having such a high adhesive strength is to be constitutedby the exposed portion of the substrate, a method may be employedwherein the second electrode layer, the semiconductor layer and thefirst electrode layer formed at the peripheral surface portion of thesubstrate as well as the peripheral portion of the substrate per se aremechanically removed. In this case, a total removal thickness of thesecond electrode layer, the semiconductor layer, the first electrodelayer and the substrate, which are removed by the mechanical means,should preferably be in the range of 5 μm to 100 μm, more preferably inthe range of 10 μm to 25 μm.

The exposed surface of the first electrode layer or of the substrateobtained in this manner may be subjected to a surface treatment using asilane coupling agent.

If the region having such a high adhesive strength is to be constitutedby a layer of a metal selected from the group consisting of Cr, Mo, Wand Ti, a method may be employed wherein the region is subjected to aprimer treatment using a treating solution containing any one of thesemetals. Alternatively, another method may be employed wherein the activeportion of the solar cell is masked, and then a metal selected from thegroup consisting of Cr, Mo, W and Ti is vapor-deposited or sputtered. Inany of these methods, there is not any particular limitation regardingthe underlying material, so that a metal selected from the groupconsisting of Cr, Mo, W and Ti may be deposited on the surface of thesecond electrode layer.

The width of the region having a high adhesive strength to theencapsulant at the peripheral portion of the substrate may be selectedso as to ensure a sufficient adhesive strength, e.g. 0.5 mm or more,more preferably 0.5 mm to 10 mm, most preferably 1 mm to 5 mm.

Since the thin film solar cell module according to the second embodimentof this invention is featured in that a periphery of the solar cellregion is entirely surrounded by a high adhesive strength region whichis larger in adhesive strength to the encapsulant, it becomes possibleto ensure an excellent adhesion to the encapsulant and to prevent thedeterioration of power-generating property due to the penetration ofwater, thereby improving the weather resistance of the solar cellmodule.

Next, this invention will be further explained in details with referenceto the following various examples.

EXAMPLE 1

FIG. 1 is a cross-sectional view of a thin film solar cell moduleaccording to Example 1. The solar cell module shown in FIG. 1 can bemanufactured as follows.

First of all, a tin oxide film (8,000 angstroms) 2 was deposited bymeans of a thermal CVD method on a glass substrate 1 made of a soda limeglass having an area of 92 cm×46 cm and a thickness of 4 mm. Thereafter,the tin oxide film was subjected to a patterning process using a laserscriber thereby forming a transparent electrode. The reference numeral 3denotes the scribed line of the transparent electrode.

As a patterning method, the substrate 1 was set on an X-Y table, andthen subjected to a partitioning work using a Q switch YAG laser. Theoperation conditions of the laser were: 532 nm in second harmonic wave,3 kHz in oscillation frequency, 500 mW in average output, and 10 nsec inpulse width. The isolation width was 50 μm and the width of the string(individual solar cell) was about 10 mm.

In order to electrically isolate the active region of the solar cellfrom the peripheral portion thereof throughout the entire circumferenceof the active region, a patterning using a laser beam was performed, inaddition to the worked portion 12 for the string isolation, at thelocation 5 mm distanced away from the periphery of the substrate. Thereference numeral 13 denotes a laser insulation-isolating line formed asa result of this patterning.

Further, a region 14 having a width of 3.5 mm for forming anelectrode-lead out wiring formed of a plated copper foil was formed onthe outside of strings 11 a and 11 b. By means of a multiple chamberplasma CVD method, an a-Si layer 4 was formed on the tin oxide film 2patterned in advance as mentioned above. Namely, a p-type a-Si:H layer,an i-type a-Si:H layer, and an n-type micro-crystalline Si:H layer weresuccessively deposited at a temperature 200° C., thereby forming alaminated a-Si layer 4 constituting a PIN junction. In order to formeach layer, SiH₄ gas was employed at a flow rate of 100 sccm, 500 sccmand 100 sccm, respectively. In the cases of forming the p-typesemiconductor layer and the n-type semiconductor layer, 2000 sccm ofB₂H₆ gas and 2000 sccm of PH₃ gas each diluted by 1000 ppm of hydrogengas were added to SiH₄ gas, respectively.

Further, in the formation of the p-type semiconductor layer, 30 sccm ofCH₄ gas was mixed into the reaction gas thereby performing thecarbonization-of the a-Si. The power employed for the formation of eachlayer was 200 W, 500 W and 3 kW, respectively, while the reactionpressure employed was 1 torr, 0.5 torr and 1 torr, respectively. Thefilm thickness of each layer formed was assumed to be 150 angstroms,3200 angstroms and 300 angstroms, respectively, in view of the timerequired for the formation of the films. After the formation of eachfilm, the substrate 1 was set on an X-Y table and then the patterning ofa-Si layer 4 was performed using a Q switch YAG laser while off-settingthe position thereof from the patterning position of the SnO₂ 2 by adistance of 100 μm. The operation conditions of the laser were: 532 nmin second harmonic wave, 3 kHz in oscillation frequency, 500 mW inaverage output, and 10 nsec in pulse width. The isolation width was setto 100 μm by defocusing the laser beam to enlarge the beam diameter. Thereference numeral 5 denotes a semiconductor-scribing line.

Subsequently, a ZnO layer (not shown) having a film thickness of 1000angstroms was formed on the patterned a-Si layer 4 by means of amagnetron sputtering method using an RF discharge and a ZnO target. Theconditions for the sputtering were: 2 mtorr in argon gas pressure, 200 Win discharge power, and 200° C. in film-forming temperature.

Then, a reverse electrode layer 6 having a film thickness of 2000angstroms was formed on the ZnO layer at room temperature by making useof an Ag target of the same magnetron sputtering device and a DCdischarge. The conditions for the sputtering were: 2 mtorr in argon gaspressure, and 200 W in discharge power.

Next, the substrate 1 was taken out-of the magnetron sputtering deviceand set on the X-Y table, and then, the Ag layer and the ZnO layer weresubjected to a patterning process using a Q switch YAG laser, therebyforming a reverse electrode-scribing line 7 which was off-set by adistance of 100 μm from the semiconductor-scribing line 5. The operationconditions of the laser were the same as those employed in theprocessing of the a-Si layer 4. The partitioning width was 70 μm and thewidth of the string was about 10 mm.

In the same manner as in the case of the tin oxide film 2, for thepurpose of electrically isolating the active region of the solar cellfrom the peripheral portion thereof throughout the entire circumferenceof the active region, a patterning using a laser beam was performed, inaddition to the isolation of string, at the location 5 mm distanced awayfrom the periphery of the substrate. The isolating width was 150 μm andthe patterning was performed so as to include the isolating portion 13of the tin oxide film 2.

Then, the entire outer peripheral portion 15 located 0.5 mm outside thispatterning line was subjected to a grinding treatment to abrade it to adepth of about 25 μm by making use of an X-Y stage and a grindingmachine having a finely adjustable (in the Z-axis direction) flat rotarygear which was developed originally by the present inventors. Namely,the entire thickness of each of the reverse electrode layer 6, the ZnOlayer, the a-Si layer and the tin oxide layer 2 was removed, and at thesame time, the surface portion of the glass substrate 1 was alsoremoved. The working speed was 3.5 μm/min.

Thereafter, a bus bar electrode 18 consisting of a solder layer 16 and acopper plating foil 17 was formed at the position 14 of theaforementioned wiring, thereby forming an electrode-lead out wiring. Theelectrode 18 was made parallel with the string.

The reverse surface of the module constructed in this manner was thencovered by a protective film 8 consisting of a vinyl fluoride film(DuPont Corporation, Tedler (tradename)) and then, sealed by allowing anEVA sheet to be thermally fused using a vacuum laminator. Subsequently,terminals were attached to the module and the resultant module wasattached to a frame.

The solar cell module obtained in this manner was measured with respectto the current/voltage properties thereof by making use of an AM 1.5solar simulator of 100 mW/cm². As a result, the solar cell module wasfound to have a short-circuit current of 1240 mA, an open-circuitvoltage of 44.2V, a fill factor of 0.68 and a maximum output of 37.3 W.

Then, both plus and minus poles of the lead-out terminal was allowed tocause a short-circuit and at the same time, a voltage of 1500V wasapplied between the terminal and the frame to measure the resistance. Asa result, the resistance was found 100 MΩ or more, thus indicating anexcellent insulation.

Finally, the module was immersed in water for 15 minutes, and then, theresistance thereof was measured in the same manner as explained above,finding also a resistance of 100 MΩ or more.

EXAMPLE 2

In the same manner as explained in Example 1, the processes up to thestep of the laser scribing of the reverse electrode 6 and the a-Si layer4 were repeated. Then, a mask consisting of an SUS plate was placed onthe active portion of the solar cell, and the resultant solar cell wassubjected to blasting of a grinding agent having an average particlediameter of about 40 μm by making use of a blast cleaner, therebymechanically removing the reverse electrode 6, the a-Si layer 4, thetransparent electrode 2 and the surface portion of the substrate 1,which are located at the peripheral portion of the substrate 1.Thereafter, a solar cell module as shown in FIG. 1 was manufactured inthe same manner as explained in Example 1, and then, measured of itsproperties in the same manner as explained in Example 1. As a result,the properties of the solar cell module was found almost the same asthose of Example 1. Namely, the solar cell module was found to have ashort-circuit current of 1240 mA, an open-circuit voltage of 44.2V, afill factor of 0.68 and a maximum output of 37.3 W.

Further, the resistance between the lead-out terminal and the frame wasfound 100 MΩ or more in both before and after the immersion thereof inwater.

Comparative Example

A solar cell module was manufactured in the same manner as explained inExample 1 except that the mechanical removal of the peripheral portionof the substrate 1 was not performed, as shown in FIG. 2. Then, thesolar cell module was measured of its properties in the same manner asexplained in Example 1. As a result, the properties of the solar cellmodule was found to have a short-circuit current of 1240 mA, anopen-circuit voltage of 43.1V, a fill factor of 0.68 and a maximumoutput of 36.3 W, thus indicating almost the same degree of propertiesas those of Example 1. However, the resistance between the lead-outterminal and the frame was found 800 kΩ before the immersion thereof inwater and 15 kΩ after the immersion thereof in water, thus indicatingmuch lower values as compared with the results of Examples 1 and 2. Thiscan be attributed to the fact that the peripheral portion of thesubstrate 1 was poor in adhesive strength of the encapsulant so thatwater was enabled to enter into the module through an interface betweenthe encapsulant and the peripheral portion of the substrate.

EXAMPLE 3

A solar cell module was manufactured in the same manner as explained inExample 1 except that part of each of the reverse electrode 6, the ZnOlayer and the a-Si layer 4, which was located at the peripheral portionof the substrate 1 was removed by means of grinding but the tin oxidefilm 2 was not removed, as shown in FIG. 5. As a result, almost the sameresults as those of Example 1 could be obtained. Namely, the solar cellmodule obtained in this manner was measured with respect to thecurrent/voltage properties thereof by making use of an AM 1.5 solarsimulator of 100 mW/cm². As a result, the solar cell module was found tohave a short-circuit current of 1240 mA, an open-circuit voltage of44.2V, a fill factor of 0.68 and a maximum output of 37.3 W.

Then, both plus and minus poles of the lead-out terminal was allowed tocause a short-circuit and at the same time, a voltage of 1500V wasapplied between the terminal and the frame to measure the resistance. Asa result, the resistance was found 100 MΩ or more, thus indicating anexcellent insulation. Furthermore, the module was immersed in water for15 minutes, and then, the resistance thereof was measured in the samemanner as explained above, finding also a resistance of 100 MΩ or more,indicating an excellent insulating property thereof.

EXAMPLE 4

A solar cell module was manufactured in the same manner as explained inExample 1 except that part of each of the reverse electrode 6, the ZnOlayer and the a-Si layer 4, which was located at the peripheral portionof the substrate 1 was removed by irradiating a laser beam. As a result,almost the same results as those of Example 1 could be obtained.

The operation conditions of the laser were: 532 nm in second harmonicwave, 10 kHz in oscillation frequency, 1.5 W in average output, and 50nsec in pulse width. The width was set to 300 μm by defocusing the laserbeam to enlarge the beam diameter. The relative moving speed of thelaser beam and the sample was 200 mm/sec.

EXAMPLE 5

A solar cell module was manufactured in the same manner as explained inExample 1 except that a Ti layer was formed on an Al layer as the secondelectrode by sputtering such that the Ti layer was exposed at theuppermost surface. In particular, the Ti layer was surely formed at theperipheral portion of the substrate 1. The thickness of the Ti layer was30 nm. As a result, almost the same results as those of Example 1 couldbe obtained.

As explained above, it is possible according to the present invention toprovide a solar cell module excellent in dielectric strength, which canbe manufactured by making use of very simple process. Further, it ispossible to obtain a solar cell module which is free from deteriorationof power-generating property due to a corrosion after sealing thereofand which can be manufactured with high productivity.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A solar cell module which comprises a laminatelayer comprising a first electrode layer, a semiconductor layer and asecond electrode layer, which are deposited on a substrate and patternedthereby to partition these layers into a plurality of solar cells whichare electrically connected with each other and sealed with anencapsulant; wherein a periphery of said electrically connected solarcells is surrounded by a high adhesive strength region, and adhesivestrength between said high adhesive strength region and said encapsulantis larger than the adhesive strength between said encapsulant and saidelectrically connected solar cells.
 2. The thin film solar cell moduleaccording to claim 1, wherein said adhesive strength between said highadhesive strength region and said encapsulant is 3 kgf/cm or more invertical peel strength.
 3. The thin film solar cell module according toclaim 1, wherein said high adhesive strength region is constituted by anexposed portion of said first electrode layer comprising a transparentconductive oxide.
 4. The thin film solar cell module according to claim1, wherein said high adhesive strength region is constituted by anexposed portion of said substrate.
 5. The thin film solar cell moduleaccording to claim 1, wherein said high adhesive strength region isconstituted by an exposed portion of said first electrode layer or saidsubstrate, which has been surface-treated with a silane coupling agent.6. The thin film solar cell module according to claim 1, wherein saidhigh adhesive strength region is constituted by a layer of a metalselected from the group consisting of Cr, W, Mo and Ti.
 7. The thin filmsolar cell module according to claim 1, wherein said encapsulant isselected from the group consisting of ethylene-vinyl acetate copolymer,polyisobutylene, polyvinylbutyral and silicone.